Tile size responsive apparatus and control



Nov. 5, 1963 F. A. LESNETT, JR 7 TILESIZE RESP ONSIVE APPARATUS AND CONTROL Filed April 20, 1961 3 Sheets-Sheet 1 QIIIIIIIMES -T 1 H m I 3 2/ k v 20 I i 22 INVENTOR l flak/ M4 [f/ZQZJ? ATTORNEYS N 1963 F. A. LESNETT, JR

TILE SIZE RESPONSIVE APPARATUS AND CONTROL Filed April 20, 1961 3 Sheets-Sheet 2 INVENTOR fiederza Ala/2e55, in

k flifjd'z A ORNEYIS' Nov. 5, 1963 F. A. LESNETT, JR 3,109,927

TILE SIZE RESPONSIVE APPARATUS AND CONTROL Filed April 20, 1961 3 Sheets-Sheet 3 7/ 97'? HIGH STEP LOW RESET, Col/WEI? ne'ssr COUNTER //0 w /02 v w 95 #4 w I W M0 70R POWER SOURCE United States Patent amass; TILE SIZE RESPONMVE APPARATUS AND CGNTRUL Frederick A. Lesnett, In, Lakeland, Fla, assigns: to

Florida Tile Industries, Inc., Lakeland, Fla a corporation of Florida Filed Apr. 20, 1961, Ser- No. 104,331 2 Claims. (Cl. 235-92) This invention relates to object size detection and control, and more particularly to apparatus responsive to the thickness of each of a number of objects moving along a traveling converter.

The invention will be described in conjunction primarily with a tile forming press of well-known type, such as that described in Crossley Patent .No. 1,790,041, but it is to be understood that the size detection and control apparatus of the present invention is capable of use in connection with other equipment than this particular type of press and in connection with other objects than tile.

The-Crossley press is of the friction-operated type and includes a die case reciprocable with respect to the bed of a press and forming with a plurality of die punches mounted on the bed, a plurality of cavities designed to receive clay dust. The die case is initially moved to an upper position to define the depth of thickness of the cavities, and a ram is then reciprocated toward and away from the cavities to compact the clay positioned therein. During the reciprocating strokes of the ram, the die case is yieldingly held in position such that it may move downwardly with the ram strokes so as to permit successive compactions of the clay. When the tiles have been compacted to the desired extent, the die case is moved downwardly to expose the tiles and the tiles are moved away from the press and onto a traveling converter which draws the tiles to various other treatment stations.

The thickness of tile formed in this manner is variable in accordance with the characteristics of the particular clay being employed at any one time, including the amount of moisture in such clay and the amount of air contained therein. Consequently, the thickness of the tile may vary from time to time, even during a single run of the press with a single bag of clay. The Crossley patent discloses apparatus for controlling the thickness of the tile by adjustment of the uppermost position to which the die case is moved to define the tile cavities. In the Crossley apparatus, a rotatable eccentric cam is mounted in the path of movement of an extension of the piston rod of an air motor which controls the reciprocating movement of the die case. If the cam is rotated in one direction, the uppermost position of the die case is raised, while if the cam is rotated in the opposite direction, the uppermost position of the die case is lowered. Since the uppermost position of the die case determines the thickness of the cavities formed for reception of the clay, it therefore determines the thickness of the tile produced during operation of the press.

The Crossley patent discloses a manual adjustment for the position of the eccentric cam. to determine tile thickness, such manual adjustment being provided through a hand wheel whose rotatable position controls the position of the cam, through a worm and gear assembly. Use of this adjustment mechanism necessarily involves measurement of the tile thickness in some way not disclosed in the Crossley patent and it has been conventional in the past to caliper selected ones of the tiles from the press, and if these tiles are all, or nearly all, outside of tolerances, the press is stopped and the cam position manually changed.

The apparatus of the present invention has for its main 2 object the automatic detection of changes in the thickness of the tile, through photoelectric sensing apparatus, thereby eliminating the manual calipering opera-tion heretotore employed. The photoelectric sensing assembly includes a pair of photocell systems respectively operable to respond to excessive thickness and excessive thinness of the tiles, as they move along the traveling conveyor from the press. However, wall tiles are customarily made with ridges on their upper surfaces, so that the thickness of a tile sensed by the photoelectric systems may be difterent for diiierent positions of the particular tile with respect to the photoelectric apparatus. In order to insure that thickness is sensed only when each tile is in the same position relative to the photoelectric system, the thickness sensing apparatus is cont-rolled by a trigger device operative only when the tile is in the selected position. The operation of this trigger apparatus is made possible by the fact that wall tile is customarily made with a plurality of lugs extending outwardly from the side surfaces of the tile. Consequently, when a plurality of such tiles are moving along a traveling conveyor, they are spaced apart by these lugs, defining slots extending along the thickness dimension of the tiles. The trigger apparatus of the present invention includes a photocell system aligned with respect to such slots and operative to permit the tolerances sensing photocell systems to take effect only when a slot between a pair of tiles is aligned with the trigger photocell system.

Though the thickness sensing apparatus of the invention is usable either by itself to form an indication of departure from tolerances or in connection with other apparatus (e.g., mechanism for discarding tiles outside of tolerances), it is particularly adapted for use in conjunction with an automatic size control-ling attachment for a tile press. Such an attachment may appropriately include, in addition to the photocell detection assembly, a motor rotatable in opposite directions under control of the two thickness-responsive photocell systems to rotate the eccentric cam in opposite directions. Thereby the size of tile produced by the press is automatically controlled and such control may take place without manual adjustment of the cam position and without stoppage of the press operation.

The invention will now be more fully described in conjunction with drawings showing a preferred embodiment thereof.

In the drawings:

FIG. 1 is a diagrammatic showing in perspective form of portions of a tile press, showing the die case and size control motor assembly in broad outline;

FIG. 2 is a diagrammatic showing of a pair of tiles mounted on a traveling conveyor, illustrating the lugs which form a slot cooperative with the trigger photocell system;

'FIG. 3 is a partly sectional view showing the die case, reciprocating air cylinder, and eccentric cam in greater detail;

FIG. 4 shows the gear train and motor operable to adjust the rotational position of the eccentric cam;

FIG. 5 is a diagrammatic view showing the relative positions of the three photocell systems of the invention; and,

FIG. 6 is a schematic diagram showing the photocell systems and cooperating electrical devices which control the rotational movement of the size-adjusting motor.

Referring first to FIG. 1, the usual friction-operated tile press includes a fixed bed 10 which is positioned above the floor by legs 11 and carries a side frame composed of cylindrical rods 12. Journaled upon the rods 12 is a slideway which supports a plunger or ram 1-4 reciprocable with respect to the bed through apparatus a 3 f the type disclosed in Crossley Patent 1,790,041. Since the portions of the apparatus which provide for reciprocable movement of the ram are not in themselves important to the present invention, they will not be disclosed herein.

The ram 14- is designed to travel downwardly into abutment with a die case 15 having a plurality of slots extending therethrough and defining with a plurality of plungers 16 a corresponding plurality of cavities designed to receive clay. Clay is customarily delivered to the die cavities of this type of press through a so-called shaker box which is shown in a co-pending application of Lesnett and Wenger, Serial No. 5,418, filed January 29, 1960, now Patent No. 3,044,138. The shaker box is not disclosed herein since it is not important per se to the functioning of the apparatus of the present invention. Sufiice it to say that the shaker box operates in conjunction with reciprocating movement of the die case to deliver measured quantities of clay dust to the cavities formed between the die case 15 and the plungers 16.

The die case 15 constitutes the upper element of a rigid rectangular frame whose lower cross-member is designated as 18 and whose side members 19 are rods which pass through the bed 10 so that the die case may be reciprocated by vertical movement of the cross-member and rods. The cross member 18 carries an air cylinder 20 which (FIG. 3) contains a piston 21 movable upwardly or downwardly with respect to the cylinder in accordance with Whether air under pressure is delivered to the upper portion of the cylinder or the lower portion thereof. The piston 21 is fixed to a piston rod 22 which in turn is fixed to the cross-member 18. The piston 21 also carries an extension 23 of the piston rod, passing out through the opposite end of the cylinder and movable with the piston with respect to an eccentric cam 24 rotatable on a shaft 25. The eccentric cam 24 determines the uppermost position of the die case, when it is moved upwardly to define the cavities for reception of the clay. It will be seen that in the position of the eccentric cam of FIG. 3, the uppermost position of the die case is the highest possible, while if the cam were rotated through 180, the uppermost position of the die case would be the lowest. correspondingly, in the position shown in FIG. 3, the thickness of the die cavities 17 is the greatest, while if the cam were rotated through 180, the thickness would be the least.

Referring now back to FIG. I, mounted on the air cylinder supporting structure is also a size control motor 26 which is controlled by the photocell systems to be described hereinafter, to rotate a pulley 27 through a belt 28, to control the position of the eccentric cam 24.

Referring now to FIGS. 2 and 5, the tiles are moved away from the press on conveyor members 30 which are appropriately pieces of polyethylene tubing on similar divided supports. In FIG. 2 there are shown two tiles 31 and 32, each of which has a pair of lugs 33 projecting outwardly from each of its four sides. These lugs are provided for by the shape of the die cavity formed in the die case 15, and are used to space the tiles apart when they are in position on a wall, so that grouting may be inserted between the tiles. The lugs necessarily space the two tiles apart and provide (FIG. a slot 34 which extends between the tiles along the thickness dimension thereof.

The spacing or slot 34 between the tiles is cooperative with a photocell system including a light source 35 and a photocell 36. As will be explained hereinafter in conjunction with FIG. 6, this photocell system operates as a trigger device to control two other pairs of photocell systems used to sense excessive thickness or excessive thinness of the tiles. The two other photocell systems include a first system having a light source 37 and a photocell 38 and a second system including a light source 39 and a photocell 40. The light source 37 and photocell 38 are arranged rearwardly with respect to the direction of travel of the tiles, from the position of the trigger photocell system including source 35 and 36, as are the light source 39 and photocell 40. The second photocell system including source 37 and photocell 38 is disposed transversely with respect to the direction of travel of the tiles with the source on the opposite side of the tile from the photocell, and with the light path extending above the light path formed between the light source 39 and the photocell 40. The position of the light path of the second photocell system defines the uppermost extent of a permissible wall-tile. That is, any tile which is thick enough to interrupt the light path of this second photocell system is too thick and must be sensed. In contrast, the light path between source 39 and photocell 40 defines the lowermost permissible extent of the thickness of a tile, so that any tile which is thin enough so that this light path is completed is too thin and must also be sensed.

Summarizing, when the tiles are in the positions shown in FIGS. 2 and 5, the light path of the first photocell system including light source 35 and photocell 36 is completed, and, if the tile is of proper thickness, the light path of the second photocell system including source 37 and photocell 38 is also completed, while the light path of the third photocell system including source 39 and photocell 40 is interrupted.

Referring now to FIG. 6, the trigger photocell 36 is therein shown as exposed to light from the filament light source 35. The source 35 is connected between ground and one terminal of a low voltage A.-C. winding 41 on power transformer 42, through a potentiometer 43 provided to control the brightness of illumination from the lamp.

The photocell 36 has one of its terminals connected to the movable contact of a potentiometer 44 which is connected at one of its ends to ground and at its other end through a voltage dropping resistor 45 to one side of the power bus 46. The power bus is connected through the power switch 47 to a suitable source of A.-C. power (not shown). The other side of the power source is connected through the second section of the power switch 47 to ground. Thereby, there is provided a Voltage divider including the potentiometer 44, so that the sensitivity of the photocell may be controlled by adjustment of the movable contact of the potentiometer. The other terminal of the photocell is connected through a capactitor 48 to the control grid of a thyratron gas discharge tube 49. The junction between capacitor 48 and photocell 36 is connected to ground through a resistor 50, while the junction between capacitor 48 and the control grid of the thyratron is connected to ground through a resistor 51. The suppressor grid of the thyratron is connected to the cathode, which in turn is connected through a second low voltage winding 52 of the power transformer 42 to ground.

The anode or plate of the thyratron 49 is connected through the winding of a relay 53 to the power bus 46. The movable contact of that relay is also connected to the power bus 46, but the normally disengaged stationary contact of the relay 54 is connected through the normally closed contacts of a thermal time delay relay 55 to one terminal of the operating coil of a trigger relay 56. The other terminal of the operating coil of the relay is connected to ground. The heating coil of the time delay relay 55 is connected between ground and the contact 54 of relay 53, through a potentiometer 57 which controls the current that will pass through that heating coil when the relay 53 is operated. The time delay relay 55 therefore insures that the trigger relay 56 cannot be energized for more than a predetermined short period by operation of relay 53.

As was indicated above, the trigger photocell 36 and' its cooperating lamp 35 are provided to insure that the tiles whose dimensions are being sensed by the photocell system are in proper position at the time of the actual sensing operation. IIhe trigger relay 56 provides this feature, because that relay must be energized before either an excessively thick or excessively thin indication can be made.

The excessively thick sensing apparatus of course includes the photocell 38 and the filament lamp source 37 which directs light upon it. The lamp source 37 is connected across the power source by connection of one of its terminals to ground and its other terminal to the coil 41 on the power transformer, through a potentiometer 60. The potentiometer of course enables the operator to control the intensity of illumination from the lamp 37 and therefore the intensity of illumination on the photocell 38. Photocell 38 has one of its terminals connected to the movable contact of the potentiometer 61 whose outside terminals are respectively connected to ground and connected to the power bus 46 through a voltage dropping resistor 62. The voltage divider formed by the poten tiometer and resistor 62 therefore furnishes a variable voltage to one side of the photocell, which voltage can be used tocontrol the sensitivity of the system. The other terminal of the photocell is connected through capacitor 63 to the control grid of thyratron 64. The junction between photocell 38 and capacitor 63 is connected to ground through a resistor 65, While the junction between capacitor 63 and the control grid is connected to ground through a resistor 66. The suppressor grid of the thyratron is connected to the, cathode, the cathode is connected to the winding 52 on the power transformer, and the anode is connected through the operating coil of a relay 67 to the power bus 46.

The movable contact of relay 67 is connected to power bus 46, but the stationary contact, which is normally disengaged from the movable contact, is connected to a movable contact 69 on the trigger relay 56. This contact 6 9 is normally disengaged from a stationary contact 70, but when the trigger relay is energized, contacts 69 and 7 are engaged, so that connection is made from the power bus 46 through the contacts of relay 67', contacts 69 and 70 of the trigger relay, to one of the step input terminals of a counter 71. Counter 71 is of any suitable type well known and available on the market which is operable to count the number of pulses which it receives and to deliver an output only when the number exceeds a preset level. The'counter may be designed to be adjustable to respond to any desired number of input pulses. The other step terminal of the counter 71 is connected to ground, so that each time that both the trigger relay 56 and the relay 67 are energized, a pulse is supplied to the counter. The operation of the counter in connection with its output circuit will be described hereinafter.

The low detection system including photocell 40* and lamp source 39 are of course positioned aligned with respect to each other, and the lamp is connected between ground and the winding 41 on the power transformer through an intensity-adjusting potentiometer 77. One terminal of the photocell 40 is connected to a potentiometer 78 whose opposite terminals are respectively grounded and connected to the power bus 46 through a voltage dropping resistor 79. The other terminal of the photocell is connected through a coupling capacitor 80* to the control grid of thyratron 81. The junction between the photocell 46 and capacitor 80 is connected to ground through resistor 82, while the junction between capacitor 8!! and the control grid is connected to ground through resistor 83'. The suppressor of the thyratron is connected to the cathode which in turn is connected to the winding 52 of the power transformer. The plate of the thyratron is connected through the operating coil of a relay 85 tothe power bus 46.

The movable contact of the relay 8 is connected to power bus 46, while the stationary contact which is normally :disengaged from the movable contact is connected to a movable contact 86 of the trigger relay 56. The corresponding normally-disengaged stationary contact 87 of the trigger relay is connected to the ungrounded step input terminal of a counter 88 which is identical to counter 71. Thereby, each time the trigger relay is energized and relay is at that time energized, a pulse is supplied to the counter 88 which is counted by the counter, and when the preset number of pulses is: counted thereby, there is an output available from the counter.

The output of the high counter '71 is supplied between terminals '90 and 91. Terminal 91 is connected through the operating coil of a relay 92 to ground. The output of low counter 88 is developed across output contacts 93 and 94. Terminals 94 and '90 are connected to ground. The output terminal 93- of low counter 88 is connected through the normally-engaged contacts of a thermal time delay relay 95 to one terminal of the operating coil of a relay 96. The other terminal of the operating coil of this relay is connected to ground. The heater winding of the time delay relay 95 is connected between ground and the terminal 93.

As a result of the connections to the relays 92 and 96, whenever the high counter 71 counts the preset number of pulses, the relay 92 is energized, while whenever the low counter 88 counts the preset number of pulses, the relay 96 is energized. For the purpose of illustration only, it will be assumed that each counter is set for six counts. This means that six successive tiles must be thicker than the predetermined limit for the relay 92 to be energized, while six successive tiles must be thinner than the predetermined limit for relay 96 to be energized.

The relays 92 and 96 have respective movable contacts 1% and 1&1 which are connected to the power bus 46. The corresponding normally-engaged stationary contacts of these relays are not connected, but the normally-disengaged stationary contact 102 cooperating with the movable contact 1% is connected to a second normally-disengaged stationary contact 103 which cooperates with movable contact 104 of the relay '92. The contact 102 is also connected through the normally engaged contacts of a thermal time delay relay 105 to the ungrounded terminal of the operating coil of relay 912.

The corresponding normally-disengaged contact 1% of the relay 96-which cooperates with the movable contact 101 is likewise connected to a normallyadisengaged stationary contact 197 which in turn cooperates with a movable contact 108. The stationary contact 107 is also connected through the normally-engaged contacts of a thermal time delay relay 109 to the ungrounded terminal of the operating coil of relay 96. One terminal of each of the heater windings of the time delay relays 105 and 109 is connected to the movable contact of a potentiometer 1110 one of whose contacts is connected to ground and the other of whose terminals is unconnected. The other terminal of the heater associated with relay 105 is connected to [the stationary contact 102, while the other terminal associated with the heater of relay 109 is connected to contact 107. These time delay relays provide holding circuits for relays 92 and 96 but also provide that neither relay may remain energized for more than a predetermined period which is controllable by adjustment of the potentiometer 1 10.

The movable contact 104 of relay 92 is connected to one terminal of the operating coil of a Down control delay 115. The other terminal of the operating coil of relay is connected to the ground. Similarly, the movable contact of the relay 96 is connected through the operating coil of an Up control relay 116 to ground.

The control relays 1115 and 116 control the direction of rotation of the motor 26. This control is effected by re versing the connections of two of the leads 120 and 121 of the motor, thereby reversing two of the phases of the motor so that it may be rotated in the opposite direction. The lead 12-2 is connected through one section of the motor control switch 123 to one terminal of a three phase motor power source (not shown). A second terminal of the power source is connected through a second I ally operated switches and 151.

section of the switch 123 to a movable contact 124 of the control relay 115. That con-tact is normally engaged with a stationary contact 125 which is connected to a movable contact 126 of the control relay 116. The corresponding normally-engaged stationary contact is unconnected, but the stationary contact 127 which is engaged with movable contact 126 when the relay 116 is energized, is connected to lead 121. Thereby, the lead 121 is connected to the power source through contacts of the two relays when the relay 116 is energized but the relay- 115 is not energized.

When the relay 115 is energized, the contact 124 is engaged with a stationary contact 128 which is connected to lead 120 of the motor.

The third terminal of the power source is connected through a section of the motor control switch 123 to a movable contact 1341 of relay 116. The normally-engaged stationary contact 131 of this relay is connected to a movable contact 132 of relay 115. The normally-engaged stationary contact corresponding to movable contact 13 2 is unconnected, but the normally-disengaged stationary contact 138 is connected to lead 121 of the motor. Thereby, when relay 116 is deenergized and relay 115 is energized, the third terminal of the power source is connected to lead 121 of the motor.

When relay 116 is energized, its movable contact 130 engages a stationary contact 134. This stationary contact is connected to lead 120,. so that, when the relay 116 is energized, the third terminal of the power source is connected to lead 120. It will be seen, therefore, that power is supplied to the motor 26 to energize it whenever either one of the control relays 1'15 and 116 is energized, but it will also be seen that the motor rotates in opposite directions depending upon which of these two relays is energized.

The mo vable contact 108 of relay 96 is connected through the operating coil of a relay 140 to ground, as well as through the operating coil of relay 116 to ground. Therefore, relay 14-0 is operated whenever relay 116 is operated. The relay 140 has a stationary contact 141 which is connected to the power bus 46 and has a movable contact 142 which is normally disengaged from the stationary contact and which is connected to the un grounded reset terminals of each of the counters 7 1 and 88. Similarly, the movable contact 10 4 of relay 92 is connected through the operating coil of a relay 14-3 to ground, as well as through the operating coil of relay 115 to ground. Thereby, whenever the control relay 115 is energized, the relay 143 is also energized. Relay 143 has a stationary contact 14 4 which is connected to the power bus 46 and also has a movable contact 145 which is connected to the ungrounded reset terminals of each of the counters 71 and 88.

As a result of these connections of relays 143 and 140, each of the counters 71 and 88 is reset to its initial zero position whenever either of the control relays 115 and 116 is energized. Of course this reset action disconnects the ungrounded output terminal from the power bus 46, for each of the counters, so that voltage is not available from these sources to energize either of the relays 92 or 96. However, these relays remain energized for a time period determined by the setting of potentiometer 110, through connection of a holding circuit for the operating coil through the contacts of the respective thermal time delay relays 105 and 109. These time delay relays control the length of time that the motor is powered to cause adjustment of the cam, each time that the motor is operated.

The apparatus of FIG. 3 is also provided with manual switching means for control of the position of the control cam. These manual means include a pair of manu- Each of these switches is of the double-pole, double-throw type. The center contacts 152 and 153 of the respective switches are connected to power bus 46. The other center contact of switch 150 is connected to an outside terminal 154 of the switch 151, while the other center contact 156 of the switch 151 is connected to an outside terminal 157 of switch 150. The outside terminal 158 of switch 150 is connected through the nonmally-open contacts of a thermal time delay relay 160 to the stationary contact 161 of control relay 96. This stationary contact is engaged with the movable contact 108 of thatrelay when the relay is de-energized. As indicated above, that movable con tact is connected through the operating coil of control relay 116 to ground. In similar fashion, the outside terminal 162 of switch 151 is connected through the nor mally-open contacts of a thermal time delay relay 163 to a stationary cont-act 164 of relay 92. That stationary contact is normally engaged with movable contact 104 of the relay, which of course is connected through the operating coil of control relay to ground. The heater coil of the relay 161) is connected between ground and the terminal 158 of switch 150, while the heater coil of time delay relay 163 is connected between ground and the terminal 162 of switch 151.

By virtue of these connections, when the switch is in its operated condition to adjust the motor downwardly, the switch 151 must be in its unoperated condition, and power is then furnished from bus 46 through the contacts 153 and 154 of switch 151, and through contact 158 of switch 150 to the heater coil of time delay relay 166. After a time delay sufiicient to cause the switch contacts of the relay to engage, a circuit is completed through the contacts 161 and 108 of the relay 96 to' the operating coil of the relay 116. Connections are then completed to energize the motor in such fashion as to move the cam upwardly.

When the switches 150 and '151 are moved to their opposite positions, power from the bus 46 is connected through contacts 152 and 157 of the switch 150 and contacts 156 and 162 of switch 151, to the. heater of time delay relay 163. After a time delay sufficient to allow the contacts of that switch to engage, a circuit is completed through the contacts 164 and 104 of the relay 92 to the operating coil of control relay 115. Then, the motor is energized in such fashion as to cause the cam to be moved downwardly. It will be seen that the switches are connected in mutually exclusive fashion, so that it is not possible for anoperator to simultaneously operate switches 150 and 15:1 to attempt to move the motor up and down at the same time.

A further feature of the electrical system of FIG. 6 which has not been described above is the safety feature provided by time delay relay 95 connected to the output of Low counter 88. That relay is employed to insure that the control relays cannot be operated at the same time to thereby short the motor power source, as might be possible if malfunction occurred.- With time delay relay 109, relay 92 would be reset by the time relay 116 was operated since the High counter 71 is connected directly to relay 92, and thereupon causes operation'of control relay 115 and reset relay 143, while the Low counter 88 is not connected to relay 96- until a predetermined time has elapsed, this time being sufficient for relay 92 to drop out before energization of relay 96.

Referring now to FIG. 4 showing the gear train interconnecting the motor 26 and the cam 24, the motor shaft drives the sprocket Wheel 171 which drives wheel 22 through chain 28. The wheel 27' is rotatably mounted on a shaft 172 but is positioned in abutting relationship with a felt disc 173 mounted on the same shaft. The felt disc is positioned between wheel 27 and a disc 174 to form a friction clutch between these two members,

and the disc 174 is keyed to shaft 172.

Shaft 172 carries a worm 175 engaged with a gear 76 fixed to shaft 25. Consequently, rotation of shaft 172 causes rotation of eccentric cam 24.

The friction clutch between the motor 26 and shaft 172 is provided to avoid possible damage to the apparatus which might occur if there were a fixed coupling therebetween and motor 26 was energized to rotate the cam to lower the uppermost position of the die case while the die case was in its uppermost position. The friction clutch, of course, permits slippage between shaft 172 and wheel 27 under such conditions, so that the cam may remain stationary.

In operation of the apparatus described hereinabove, as the tiles pass between the light sources and photocells of the three photocell systems, whenever the tiles are within tolerances, the light path between the second source 37 and its photocell 38 remains completed, so that no change in illumination of the photocell occurs. In the illustrated embodiment, the photocells are of the photoconductive type, so that no change in current in the circuit consisting of resistor 63, photocell 33, potentiometer 61 and resistance 62, occurs, other than that due to the cyclic nature of the A.-C. source applied across that cir-' cuit. The potentiometer 62 is then adjusted so that the voltage at the grid of thyratron 64 is always less than the critical voltage and the tube does not fire.

At the same time the light path between the third light source 39 and the third photocell 40 remains interrupted, and thyratron 8 1 does not fire. The first or trigger photocell system, however, has its light path periodically interrupted and completed as each tile passes the size detection assembly, and a pulse of voltage is passed through capacitor 48 to the control grid of thyratron 49 each time that the light path is completed through slot 34. The thyratron fires upon receipt of each such pulse, thereby causing relays 53 and 56 to energize, but since neither of thyratrons 64 and 84 is fired, the trigger thyratron does not affect counters 71 or 88.

In the event that a tile thicker than the predetermined outside limit passes through the size detection assembly, however, the light path between source 37 and photocell 38 is interrupted. The resulting pulse of current in the photocell circuit is passed to the control grid of thyratron 64 through capacitor 63, and the thyratron fires, energizing relay 67. When the tiles then reach a position such that the light path between source 35 and photocell 36 is completed through slot 34, thyratron 49 fires to energize relay 53 and trigger relay 56. A circuit is then completed from power bus 46, through the contacts of relay 67, contacts 69 and 70 of trigger relay 56 and the step input circuit of High counter 71 to ground. The counter thereby advances by one count. Then, as the tiles continue their motion past the size sensing assembly, the light path of the trigger photocell system is interrupted, thyratron 49 extinguishes and trigger relay '56 drops out. If the succeeding tiles are also too thick, the above operations will repeat until the predetermined count of High counter 71 is reached. Then an output will be available at relay 92 to energize that relay and connect the operating coil of Down control relay 115 across the power source through contacts 100 and 192 and 103 and 164 of relay 92. Reset relay 143 is simultaneously energized to supply energizing voltage to the reset circuit of High counter 71 through contacts 144 and 145 of relay 143. Relay 92 does not release at this time, however,

because a holding circuit therefore is completed through time delay relay 105.

With the energization of control relay 115, leads 120 122 of the size control motor are connected to the power source to cause the motor to rotate in such direction as to rotate the cam 24 to lower the uppermost position of the die case. This action results in decrease of the thickness of the cavities 17, thus causing decrease in the amount of clay compacted by the cam 14 and corresponding decrease in the thickness of the tiles.

The extent of rotation of cam 24 is determined by the setting of the potentiometer 110 and is normally such that only a slight adjustment of tile thickness occurs before relay 106 disengages its contacts to de-energize relay 92, and hence control relay 115.

If the tiles continue to be too thick, the above-described operations are repeated to cause further movement of cam 24 to further lower the uppermost position of the die case.

If the tiles passing the size detection assembly are too thin, the light path between source 39 and photocell 40 is completed, thereby causing firing of thyratron S1 and operation of relay 85. Then, each time that a slot 34 appears opposite the light path of the trigger photocell system, the Low counter 88 is stepped through successive conditions. When the predetermined count is reached, energizing voltage is available at the output of the counter and, after a time delay determined by relay 95, the Low relay 96 is energized. Then, through operation of control relay 116 the leads 12tl122 are connected to the power source, but with leads 120 and 122 connected to different phases of the three phase supply. The motor 26 then rotates in the opposite direction to rotate cam 24 in such direction as to raise the uppermost position of the die case.

As was indicated above, the size sensing apparatus of the invention could be used for other purposes than automatic adjustment of the size. For instance, it could be used to furnish an indication of size outside of tolerances, so that manual adjustment could then be made in the manner suggested in Crossley Patent No. 1,790,041. Alternatively, the size sensing apparatus could be employed to reject tiles outside of tolerances, as by moving them 011 the conveyor or by energizing a knife solenoid to cause a knife to break the tile, whereupon the tile would fall between the conveyor tubes.

While photocell systems using photoconductive devices such as the usual selenium cells, have been specifically disclosed in this application, it will be understood that other types of photocells could be employed. Specifically, photo-voltaic cells could be used, with appropriate modifications in the circuits controlled thereby.

Many other minor changes could be made in the apparatus specifically disclosed herein, without departure from the scope of the invention. Accordingly, the invention is not to be considered limited to the specific embodiment shown, but rather only by the scope of the appended claims.

I claim:

1. Apparatus for sensing Whenever objects spaced apart on a travelling conveyor by a predetermined distance are outside of tolerances in thickness comprising first, second and third photocell systems each including a source of light energy and a photocell spaced apart transverse to the direction of travel of the objects, the first photocell system being aligned parallel to the thickness dimension of the objects and positioned in such fashion that the objects prevent light from the source from reaching the associated photocell except when the spacing between objects is opposite said first photocell system, the second and third photocell systems being aligned transversely to said thickness dimension sufficiently rearwardly with respect to said direction of travel that an object is positioned between the light source and the photocell of each of said second and third photocell systems whenever the spacing between objects is opposite said first photocell system, with the second system positioned such that light from the source reaches the photocell except when the object is thicker than a first predetermined limit and the third system positioned such that light from the source reaches the photocell only when the object is thinner than a second predetermined limit, and means connected to each of said photocell systems responsive to each interruption of the light path of said second photocell-system and completion of the light path of said third photocell system only when the light path of said first photocell system is completed, said last-named means including first, second and third thyratron tube circuits and first, second and third relays, each of said thyratrons being connected to corresponding ones of the photocells of said systems, the photocell of said first and third systems being respectively operable to fire the thyratrons of said first and third thyratron circuits when the light paths thereof are completed and the photocell of said second system being operable to fire the thyratron of said second thyratron circuit when the light path thereof is interrupted, said thyratrons being connected to corresponding ones of said relays and each operable to energize its associated relay when it fires, a trigger relay connected to said first relay and operable to be energized thereby when the thyratron of said first thyratron circuit is fired, a first and a second counter each operable to supply an output only when energizing voltage has been supplied thereto a predetermined number of times, means including normally disengaged contacts of said second relay and a first set of normally disengaged contacts of said trigger relay operable to supply energizing voltage to said first counter only when both of said trigger relay and said second relay are energized, and means including normally disengaged contacts of said third relay and a second set of normally disengaged contacts of said trigger relay operable to supply energizing voltage to said second counter only when both of said trigger relay and said third relay are energized.

2. The apparatus of claim 1 in which said last-named means further includes a high relay and a low relay, said first counter being operable to energize said high relay when it reaches its predetermined count and said second counter being operable to energize said low relay when it reaches its predetermined count, means for resetting each counter upon energization of either one of said high and low relays, and means for maintaining each of said high and low relays energized for a predetermined period of time after energization thereof by its associated counter.

References Cited in the file of this patent UNITED STATES PATENTS 2,033,645 Parkhill Mar. 10, 1936 2,051,781 Brown Aug. 18, 1936 2,085,671 Powers June 29, 1937 2,229,489 Barnard Jan. 21, 1941 2,231,186 Gould Feb. 11, 1941 2,289,933 Rankin July 14, 1942 2,446,046 Hurley July 27, 1948 2,635,747 Hughes Apr. 21, 1953 2,843,321 Sloan July 15, 1958 2,869,788 Turner Jan. 20, 1959 2,930,526 Hendrickson Mar. 29, 1960 2,999,944 Laycak Sept. 12, 1961 FOREIGN PATENTS Great Britain Apr. 11, 

1. APPARATUS FOR SENSING WHENEVER OBJECTS SPACED APART ON A TRAVELLING CONVEYOR BY A PREDETERMINED DISTANCE ARE OUTSIDE OF TOLERANCES IN THICKNESS COMPRISING FIRST, SECOND AND THIRD PHOTOCELL SYSTEMS EACH INCLUDING A SOURCE OF LIGHT ENERGY AND A PHOTOCELL SPACED APART TRANSVERSE TO THE DIRECTION OF TRAVEL OF THE OBJECTS, THE FIRST PHOTOCELL SYSTEM BEING ALIGNED PARALLEL TO THE THICKNESS DIMENSION OF THE OBJECTS AND POSITIONED IN SUCH FASHION THAT THE OBJECTS PREVENT LIGHT FROM THE SOURCE FROM REACHING THE ASSOCIATED PHOTOCELL EXCEPT WHEN THE SPACING BETWEEN OBJECTS IS OPPOSITE SAID FIRST PHOTOCELL SYSTEM, THE SECOND AND THIRD PHOTOCELL SYSTEMS BEING ALIGNED TRANSVERSELY TO SAID THICKNESS DIMENSION SUFFICIENTLY REARWARDLY WITH RESPECT TO SAID DIRECTION OF TRAVEL THAT AN OBJECT IS POSITIONED BETWEEN THE LIGHT SOURCE AND THE PHOTOCELL OF EACH OF SAID SECOND AND THIRD PHOTOCELL SYSTEMS WHENEVER THE SPACING BETWEEN OBJECTS IS OPPOSITE SAID FIRST PHOTOCELL SYSTEM, WITH THE SECOND SYSTEM POSITIONED SUCH THAT LIGHT FROM THE SOURCE REACHES THE PHOTOCELL EXCEPT WHEN THE OBJECT IS THICKER THAN A FIRST PREDETERMINED LIMIT AND THE THIRD SYSTEM POSITIONED SUCH THAT LIGHT FROM THE SOURCE REACHES THE PHOTOCELL ONLY WHEN THE OBJECT IS THINNER THAN A SECOND PREDETERMINED LIMIT, AND MEANS CONNECTED TO EACH OF SAID PHOTOCELL SYSTEMS RESPONSIVE TO EACH INTERRUPTION OF THE LIGHT PATH OF SAID SECOND PHOTOCELL SYSTEM AND COMPLETION OF THE LIGHT PATH OF SAID THIRD PHOTOCELL SYSTEM ONLY WHEN THE LIGHT PATH OF SAID FIRST PHOTOCELL SYSTEM IS COMPLETED, SAID LAST-NAMED MEANS INCLUDING FIRST, SECOND AND THIRD THYRATRON TUBE CIRCUITS AND FIRST, 